Comparative Environmental Impact Assessment of a Daily Electricity Restitution Operated by Advanced Adiabatic Compressed Air Energy Storage Systems (A-CAES)

Renewable energy storage is essential to address the intermittent nature of renewable sources. Beyond widely used Li-ion batteries and Pumped Hydro Energy Storage (PHES), Advanced Adiabatic Compressed Air Energy Storage (A-CAES) offers promising potential, although it is not yet commercially available in Europe. This study evaluates the environmental impacts and exergy demand of daily electricity discharge over 30 years for both 10 and 100 MWe A-CAES systems. The 10 MW system is compared to Li-ion batteries (NMC/Graphite, LFP/Graphite, and NMC/LTO chemistries), while the 100 MW system is compared to PHES. Analyses are conducted at both endpoint (human health, ecosystems, and resources) and midpoint levels (climate change and exergy demand). Results show that the 10 and 100 MW A-CAES systems have similar or higher impacts compared to their counterparts when coupled with the French electricity grid mix. This is primarily due to the impacts associated with the electricity to be stored and round-trip efficiency losses: Li-ion batteries and the PHES system have higher efficiency (79.1% and 82%, respectively) than A-CAES systems (54.4% for the 10 MW and 70% for the 100 MW). However, when coupled with renewable sources, which have lower impacts than the French grid mix, A-CAES systems are more beneficial due to lower equipment life cycle impacts, particularly for the 10 MW A-CAES (equipment impact: 11 gCO₂eq/kWh returned to the grid) compared to Li-ion batteries (equipment impact: 54 gCO₂eq/kWh returned to the grid). The study highlights A-CAES as a viable long-term storage alternative within a cradle-to-grave framework, though it acknowledges limitations, such as differences in technology readiness level (TRL) and the need for measured data to strengthen comparisons with established solutions.